CN110537340B

CN110537340B - Transmission apparatus and method, in particular for low throughput networks

Info

Publication number: CN110537340B
Application number: CN201880024182.2A
Authority: CN
Inventors: 纳比尔·斯文·洛金
Original assignee: Sony Semiconductor Solutions Corp
Current assignee: Sony Semiconductor Solutions Corp
Priority date: 2017-04-12
Filing date: 2018-04-12
Publication date: 2022-08-16
Anticipated expiration: 2038-04-12
Also published as: US20210083800A1; CN110537340A; WO2018189312A1; US20220311540A1; US11736229B2; US11265103B2; KR20190122831A; KR102255094B1; EP3610591A1

Abstract

A transmitting device, in particular for low throughput networks, comprising: an FEC encoder configured to encode the payload data into FEC codewords each having a predetermined codeword length; and a frame forming section configured to form a frame having a predetermined frame length. The frame comprises a first frame portion having a first predetermined length which is an integer multiple of the predetermined codeword length, and a second frame portion having a second predetermined length which is shorter than the predetermined codeword length. The frame formation is configured to include the FEC codeword and a predetermined number of repetitions of the FEC codeword into a first frame portion of the frame, and to include a selected number of bits of the FEC codeword into said second frame portion of the frame.

Description

Transmission apparatus and method, in particular for low throughput networks

Technical Field

The present disclosure relates to a transmitting apparatus and a corresponding transmitting method, in particular for Low Throughput Networks (LTNs) for internet of things (IoT) applications or for similar networks. The disclosure also relates to a receiving apparatus and a corresponding receiving method, in particular for LTN.

Background

The ETSI standardization group working on LTN technology recently released a first specification of IoT networks dedicated to low throughput communication (including GS LTN 001 containing use cases, GS LTN 002 describing functional architectures, and GS LTN 003 defining protocols and interfaces). LTN technology is a wide area unidirectional or bidirectional wireless network with key differences compared to existing networks. It enables long-range data transmission (distances of about 40km in open fields) and/or communication with underground buried equipment and operates with minimal power consumption, even with standard batteries, for years. The technique also enables advanced signal processing, providing effective protection against interference.

Therefore, LTN is particularly suitable for low throughput machine-to-machine communication where the amount of data is limited and low latency is not strongly required. Applications include remote metering, smart metering of water, gas or electricity distribution, location or smart urban applications (such as air pollution monitoring or public lighting). LTNs may also cooperate with cellular networks to address use cases requiring redundant, supplemental, or alternative connections.

LTN IoT networks have a similar topology as existing networks for high data rates and dynamically adapt power and frequency in the same way, but will also manage new requirements regarding power consumption and the number of base stations needed to cover the entire country. Low power, very low throughput, long battery life, simple, efficient and robust radio communication principles are key features of the first ETSI LTN specification.

There is a need to define efficient transport streams and their construction for use in LTNs.

The "background" description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

Disclosure of Invention

It is an object of the present invention to provide a transmitting apparatus and a corresponding transmitting method, in particular for LTNs for constructing efficient transport streams. It is a further object of the invention to provide a corresponding receiving apparatus and a corresponding receiving method, in particular for LTN, as well as a corresponding computer program for implementing said methods and a non-transitory computer-readable recording medium for implementing said methods.

According to an aspect, there is provided a transmitting apparatus, in particular for LTN, comprising:

-an FEC encoder configured to encode the payload data into FEC codewords each having a predetermined codeword length, an

-a frame formation section configured to form a frame having a predetermined frame length, wherein the frame comprises a first frame portion having a first predetermined length being an integer multiple of the predetermined codeword length, and a second frame portion having a second predetermined length being shorter than the predetermined codeword length, wherein the frame formation section is configured to include an FEC codeword and a predetermined number of repetitions of the FEC codeword into the first frame portion of the frame, and to include a selected number of bits of the FEC codeword into the second frame portion of the frame.

According to another aspect, there is provided a receiving apparatus, in particular for LTN, comprising:

-a frame extraction section configured to extract one or more frames from the received transport stream, a frame comprising payload data encoded as FEC codewords each having a predetermined codeword length and having a predetermined frame length, wherein a frame comprises a first frame portion having a first predetermined length being an integer multiple of the predetermined codeword length and a second frame portion having a second predetermined length being shorter than the predetermined codeword length, wherein the frame extraction section is configured to extract the FEC codewords and a predetermined number of repetitions of the FEC codewords from the first frame portion of the frame and to extract a selected number of bits of the FEC codewords from the second frame portion of the frame, and

-an FEC decoder configured to decode payload data from FEC codewords extracted from the frame, repetitions of the FEC codewords, and a selected number of bits of the FEC codewords.

According to another aspect, there is provided a computer program comprising program means for causing a computer to carry out the steps of the methods disclosed herein when said computer program is carried out on a computer, and a non-transitory computer-readable recording medium having stored thereon a computer program product which, when executed by a processor, causes the methods disclosed herein to be carried out.

Embodiments are defined in the dependent claims. It shall be understood that the disclosed method, the disclosed computer program and the disclosed computer readable recording medium have other embodiments similar and/or identical to the claimed apparatus and as defined in the dependent claims and/or disclosed herein.

An aspect of the present disclosure is to propose an efficient frame construction for LTNs, by which an improved decoding can be achieved and an error rate can be improved, among other things. A frame may be made up of several repetitions of the FEC codeword, also including a part of the codeword. An optimal choice for such partial rereading is proposed.

The foregoing paragraphs have been provided by way of general introduction and are not intended to limit the scope of the appended claims. The embodiments and further advantages will be best understood by reference to the following detailed description when read in conjunction with the accompanying drawings.

Drawings

A more complete appreciation of the present disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

fig. 1 is a diagram showing an example of transmitting the same packet multiple times in the new communication method.

Fig. 2 is a diagram illustrating an example of receiving a packet at a receiving side in the new communication method.

Fig. 3 is a diagram showing an example of frequency hopping.

Fig. 4 is a diagram showing an example of a radio system in which interference may occur.

Fig. 5 is a diagram showing an example of interference occurring when frequency hopping is performed in a wireless system.

Fig. 6 is a diagram showing a configuration example of a position notification system as an embodiment of a wireless system to which the present technology is applied.

Fig. 7 is a block diagram showing a configuration example of the transmitting apparatus 101.

Fig. 8 is a block diagram showing a configuration example of the reception apparatus 112.

Fig. 9 is a diagram showing an example of data in the first format processed by the transmitting apparatus 101.

Fig. 10 is a diagram showing an example of data in the second format processed by the transmitting apparatus 101.

Fig. 11 is a block diagram showing a configuration example of the key stream generation unit 211.

Fig. 12 shows a first embodiment of a frame.

Fig. 13 shows a second embodiment of a frame.

Fig. 14A to 14H show several embodiments of repeating different parts of the code word in the second frame portion of the frame as shown in fig. 12.

Fig. 15A to 15I show several embodiments of repeating different parts of the code word in the second frame portion of the frame as shown in fig. 13.

Detailed Description

First, an overview of a new communication method of LPWA (low power wide area) communication to which the present technique is applied will be described. LPWA communication is wireless communication used in, for example, an IoT device so as to transmit a small amount of information (such as sensor information) capable of transmitting information in a wide range of several tens to 100 kilometers with low power consumption. In the new communication method, for example, the wireless signal is transmitted in an unlicensed 868 or 920MHz band. In this case, it can be said that the new communication system is a wireless communication in the 920MHz band.

In japan, the 920MHz band is a band released by the department of internal and communication in 7 months 2011, and anyone can use it without a license. However, with regard to wireless communication in the 920MHz band, the maximum continuous transmission time is limited to 4 seconds by regulation (radio industry and business association, ARIB, (STD T-108)). Further, if the continuous transmission time is shortened to, for example, 0.4 second or less, the influence of interference on other systems using the same frequency band can be reduced. Therefore, in the ARIB rule of the 920MHz band, it is prescribed that more channels are allocated by setting the continuous transmission time to 0.4 seconds or less. As a result, if set to 0.4 second or shorter, transmission and reception can be performed with less interference. If the continuous transmission time is further shortened to 0.2 seconds or less, the pause time can be shortened and retransmission can be performed. In the new communication method, for example, the same packet is transmitted multiple times in order to improve the S/N ratio (signal-to-noise ratio, SNR) of the received signal on the receiving side.

In fig. 1, a Superframe (Superframe) of 1 minute is set, during which the same packet has been transmitted ten times. In the new communication method, the transmitting side performs carrier sensing (carrier sensing) at the time of transmission. In the new communication method, for carrier sensing, for example, as shown in fig. 1, a superframe of one minute is set for ten packet transmissions.

The receiving side receives up to ten packets from the transmitting side and synthesizes these (ten) packets as shown in fig. 2, thereby generating a combined signal (if the signal quality is not good enough, the receiver may find only less than ten packets from the transmitted signal). Then, the receiving side extracts data from the composite signal and outputs it by performing decoding (error correction) or the like on the composite signal. In this way, by combining these groups to generate a combined signal, the S/N ratio can be improved. For example, if 10 packets can be added (synthesized), the S/N ratio can be improved by about 10 dB.

Therefore, in the new communication method, even if the S/N ratio of one packet is low, the receiving side can acquire data, thereby enabling longer-distance information transmission. In addition, in the new communication method, by setting the packet transmission time to 0.2 seconds or less, or 0.4 seconds or less as described above, more frequency channels can be used without being limited by the ARIB rule. With the new communication method, for example, frequency hopping using a plurality of carrier frequencies can be performed.

Fig. 3 is a diagram showing an example of frequency hopping. In the frequency hopping of fig. 3, five channels CH 1 to CH 5 are prepared, and each packet is selected by transmitting one of the five channels. As the channel selection method, a method of increasing the number of transmission channels according to the transmission order, a method of determining the number of transmission channels according to a predetermined mathematical expression, a method of randomly selecting the number of transmission channels, or the like can be used. According to this frequency hopping, the occurrence of interference can be reduced.

Fig. 4 is a diagram showing an example of a radio system in which interference may occur. The radio system of fig. 4 has a plurality of transmitters (transmitter a to transmitter C) and receivers. In the wireless system of fig. 4, a plurality of transmitters sometimes simultaneously transmit radio signals at the same carrier frequency. When a plurality of transmitters simultaneously transmit radio signals at the same carrier frequency, interference occurs in the receiver, and it becomes difficult to correctly receive the radio signals from each of the plurality of transmitters.

The frequency hopping of figure 3 is therefore applied to the radio system of figure 4. In this case, the possibility that the carrier frequencies become the same can be reduced, and the occurrence of interference can be suppressed correspondingly. However, since the wireless system of fig. 4 is one-way communication, carrier frequencies of a plurality of transmitters may be the same even if frequency hopping is performed, and it is difficult to make interference not generated at all.

Fig. 5 is a diagram showing an example of interference occurring when frequency hopping is performed in a wireless system. In fig. 5, frequency hopping is performed in the transmitters a and B. Meanwhile, however, when a certain packet transmitted from the transmitter a and a certain packet transmitted from the transmitter B have the same carrier frequency, radio signals (packets) of the transmitters a and B collide with each other. In this way, if collision of wireless signals occurs, it is impossible for the receiver to separate packets from different transmitters, and an error may occur in finally acquired data.

For example, in fig. 5, it is assumed that the receiver is receiving a radio signal from the transmitter a. Then, one of the packets transmitted from the transmitter a collides with the packet transmitted from the transmitter B, and the wireless signal transmitted from the transmitter B is transmitted from the transmitter a. Assuming it is stronger than the radio signal. In this case, the receiver combines the colliding packets of sender B into a packet from sender a. Therefore, there is a possibility that an error occurs in the synthesized signal and data cannot be extracted. In this case, it is possible that the transmission and reception of 10 packets in the superframe are all wasted.

In bi-directional communication, retransmissions may be prompted, for example, by exchanging necessary information between the respective transmitters a and B and the receiver. However, in the one-way communication, it is difficult to supply information from the receiving side to the transmitting side, and therefore it is difficult to take a countermeasure against packet collision that can be performed by the two-way communication.

Fig. 6 is a diagram showing a configuration example of a position notification system as an embodiment of a wireless system to which the present technology is applied. The position notification system 100 of fig. 6 includes transmission devices 101(101-1 to 101-3), base stations 102(102-1 and 102-2), a cloud server 103, and an information processing terminal 104. In the position notification system 100, a position monitoring service for monitoring the position of the transmitting apparatus 101 is provided by the transmitting apparatus 101 performing radio communication with the base station 102 by a new communication method.

The transmission apparatus 101 is an embodiment of a transmission apparatus to which the present technology is applied, and transmits position information indicating its own position as a radio signal. The base station 102 has a receiving device 112. The reception device 112 is one embodiment of a reception device to which the present technology is applied, and receives a radio signal from the transmission device 101, acquires position information of the transmission device 101, and transmits the position information and the like to the cloud server 103. Therefore, the base station 102 having the reception apparatus 112 functions as a relay station that relays information transmitted from the transmission apparatus 101 and transmits it to the cloud server 103. The cloud server 103 manages various information such as location information of each transmission apparatus 101, and provides, for example, a service for notifying a user of the location of the transmission apparatus 101. For example, the information processing terminal 104 operated by a user who wants to know the position of the transmission apparatus 101 accesses the cloud server 103, acquires the position information of the transmission apparatus 101, and displays it together with, for example, map data or the like of the position to the transmission apparatus 101.

The transmitting device 101 carries the object to an object (e.g., an elderly person, etc.) that the user wants to monitor. The transmission device 101 has a position sensor that acquires its own position information using, for example, GNSS (global navigation satellite system). That is, the transmitting apparatus 101 has, for example, a receiving mechanism for receiving a GPS (global positioning system) signal from a GPS satellite as a position sensor, and obtains its own position information (e.g., latitude and longitude, etc.) as appropriate. The transmitting device 101 transmits the position information as a radio signal under appropriate conditions.

It should be noted that various types of sensors other than the position sensor are mounted on the transmission device 101, and the transmission device 101 may transmit the sensor information output by the sensors using radio signals. For example, a sensor that senses biological information such as pulse and heart rate, a sensor that senses temperature, humidity, and the like, a sensor that detects opening and closing of a door, and the like may be mounted on the transmitting device 101.

In fig. 6, the transmitting device 101-1 is carried by the elderly 111-1 in tokyo, and the transmitting device 101-2 is carried by the elderly 111-2 in the shores. The transmitting device 101-3 is carried by the elderly 111-3 of the validada. Further, the transmitting apparatus 101 has unique identification Information (ID). For example, in fig. 6, the identification information of the transmitting device 101-1 is 0001 (ID: 0001), the identification information of the transmitting device 101-2 is 0002 (ID: 0002), and the identification information of the transmitting device 101-3 is 0003 (ID: 0003), respectively. The identification information of the transmission apparatus 101 is registered in the cloud server 103.

The position monitoring target is arbitrary. For example, the object monitoring the location may be a child, an animal such as a dog or cat (pet), a company employee, or the like. Although three transmission apparatuses 101 are shown in fig. 6, the number of transmission apparatuses 101 is arbitrary. The transmission apparatus 101 may be configured as a dedicated device, but it may be incorporated in a portable information processing device such as a mobile phone or a smartphone.

The base station 102 may be of any type. For example, the base station 102 may be a dedicated facility/building. Further, for example, base station 102 may be installed in a roof of a building, such as a general building, apartment, house, roof, and so forth. Further, for example, the base station 102 may be a portable device that can be carried by a user or installed in a mobile body such as an automobile.

A plurality of base stations 102 are installed. For example, in the case of fig. 6, the base station 102-1 is disposed in tokyo and the base station 102-2 is installed on fuji mountain. Although fig. 6 shows two base stations 102, the number of base stations 102 is arbitrary.

The base station 102 has a receiving means 112. The reception device 112 receives a radio signal from the transmission device 101, and provides information (data) included in the radio signal to the cloud server 103. Further, the reception apparatus 112 requires a parameter set (e.g., modulation rate of a wireless signal, on/off of frequency hopping, etc.) as wireless format information for determining a wireless format of wireless communication from the cloud server 103, thereby acquiring the information. The method by which the reception apparatus 112 acquires information from the cloud server 103 is arbitrary.

The configuration of the cloud server 103 is arbitrary, and may be constituted by an arbitrary number of servers and an arbitrary number of networks, for example. A plurality of cloud servers 103 may be provided.

In such a position notification system 100, the transmitting device 101 performs frequency hopping setting based on its own identification Information (ID). That is, the transmission apparatus 101 sets the transmission timing and the transmission frequency of each packet based on the identification information, and transmits each packet based on the setting. As described above, by performing transmission using frequency hopping, occurrence of interference can be suppressed. That is, information can be transmitted more reliably.

Further, by setting the transmission timing and the transmission frequency based on the identification information, the transmission apparatus 101 can change the pattern of the transmission timing and the transmission frequency of each transmission apparatus 101. In this case, it is possible to suppress the occurrence of collision between packets transmitted from different transmission apparatuses 101. That is, information can be transmitted more reliably.

In addition, the reception apparatus 112 of the base station 102 acquires the identification information of the transmission apparatus 101 from the cloud server 103 and performs reception based on the identification information. That is, based on the identification information, the reception apparatus 112 sets the reception timing and the reception frequency in the same manner as the transmission timing and the transmission frequency setting of the transmission apparatus 101. It is sufficient to detect the packet regarding the transmission timing and the transmission frequency if the transmission timing and the transmission frequency of the packet can be specified by the identification information of the transmitting apparatus 101 in the receiving apparatus 112 (that is, the reception timing and the reception frequency change so that the packet is easily detected even when the S/N ratio is low). Therefore, higher sensitivity reception can be achieved. That is, more reliable information transmission can be achieved. In addition, it is not necessary to perform processing such as packet detection in an unnecessary timing and an unnecessary frequency band, and thus an increase in load can be suppressed.

In addition, the priority may be attached to the identification information of the transmitting apparatus 101. In the case where the priority is attached to the identification information of the transmission apparatus 101 acquired from the cloud server 103, the reception apparatus 112 selects the radio wave from the transmission apparatus 101 identified by the identification information according to the priority of the identification information. A signal (packet) may be received. In this case, more reliable information transmission can be achieved.

It should be noted that the reception apparatus 112 transmits information on the reception of the radio signal, for example, when receiving the radio signal from the transmission apparatus 101, transmits the content of the radio signal (data extracted from the radio signal) to the server 103.

The cloud server 103 registers and manages information about the transmission apparatus 101 (also referred to as terminal information) and information about the user (also referred to as subscriber information) in advance. The terminal information may include, for example, identification information of the transmitting apparatus 101, information of transmission frequency, a main location, and the like. Further, the subscriber information may include, for example, the name, age, sex, address, payment information of the user (person who receives the location notification service), identification information of the transmitting apparatus to be used, a login ID, a password, and the like. Of course, the terminal information and the subscriber information may include any information, respectively, and the present invention is not limited to the above-described example.

Further, the cloud server 103 transmits the identification information of the transmitting apparatus 101 to the receiving apparatus 112 of the base station 102 (some or all of the base stations 102) at a predetermined timing or in response to a request or the like from the receiving apparatus 112. At this time, the cloud server 103 may supply the base station 102 with identification information of the transmission apparatus 101 whose radio signal the base station 102 is likely to receive. In other words, the cloud server 103 cannot supply the base station 102 with the identification information of the transmission apparatus 101 for which the base station 102 is unlikely to receive its radio signal. By so doing, unnecessary packet detection in the receiving apparatus 112 of the base station 102 can be reduced, and an increase in load can be suppressed.

Furthermore, as the number of transmitting devices 101 to be received by base station 102 increases, the probability of packet collisions occurring increases accordingly. That is, since the probability that a packet from the transmitting apparatus 101 which is unlikely to receive a radio signal will arrive is small, the probability that a packet collision actually occurs is not high. However, in setting the reception timing and the reception frequency performed in the base station 102, as the number of target transmission apparatuses 101 increases, the probability of occurrence of packet collisions also increases. As described above, when packet collision occurs in the setting of the reception timing and the reception frequency, the reception of the packet is omitted. Therefore, if the receiving apparatus targets the transmitting apparatus 101 that is unlikely to receive the radio signal, the reception sensitivity is unnecessarily lowered, and the reliability of information transmission may be unnecessarily lowered. As described above, the cloud server 103 does not supply identification information of the transmission apparatus 101 for which the base station 102 is unlikely to receive a radio signal, so that the base station 102 transmits such a transmission apparatus 101 as a reception target. In this case, it is possible to suppress a decrease in the reception sensitivity and realize more reliable information transmission.

Further, the cloud server 103 acquires reception information obtained by receiving a radio signal from the reception device 112 of the base station 102. For example, based on the received information, the cloud server 103 records a history of information transmission/reception between the transmission apparatus 101 and the reception apparatus 112 (e.g., from which transmission apparatus 101 a radio signal is transmitted to the base station 102, when the reception apparatus 112 receives it, and the like). Based on the history, the cloud server 103 selects the transmitting device 101 that supplies the identification information to the base station 102, and according to the selection result, the cloud server 103 transmits the identification information (LEID (expected ID list)) and supplies it to the receiving device 112 of the base station 102. In this way, by supplying the identification information of the transmission apparatus 101 to the reception apparatus 112 of each base station 102 based on the past communication history transmitted by the reception apparatus 112 of each base station 102, the radio signal of each transmission apparatus 101 can be determined more accurately. Therefore, each base station 102 can achieve more reliable information transmission.

Further, the cloud server 103 may provide, for example, the position of the transmission device 101 (the elderly 111) to the information processing terminal 104 based on the reception information from the reception device 112.

It should be noted that the identification information of the transmitting apparatus 101 may be supplied from the cloud server 103 to the base station 102 in any form. For example, the cloud server 103 may supply the identification information of the transmission apparatus 101 to the base station 102 as a priority list. The priority list is information including a list of identification information of the transmission apparatus 101 for which the base station 102 supplied with the priority list is likely to receive a radio signal. For example, the cloud server 103 generates and supplies a priority list of the base stations 102 to each base station 102, and the base station 102 that has been supplied with the priority list transmits a transmission in which identification information is indicated in the priority list. May be processed to receive radio signals from device 101. In addition, the reception priority of the base station 102 may be added to the identification information of the transmitting apparatus 101 supplied to the base station 102. For example, the priority list may include a priority of each identification information. Then, the base station 102 supplied with the priority list can set the priority order of signal reception and the like based on the priorities included in the priority list. By doing so, the cloud server 103 can control not only the transmitting device 101 in which the base station 102 receives the radio signal but also the priority order of reception. It is also possible to obtain a communication distance from the difference between the position where the base station 102 is located and the position information transmitted by the transmission apparatus 101, and change the priority in accordance with the communication distance.

Fig. 7 is a block diagram showing a configuration example of the transmitting apparatus 101. The transmission apparatus 101 includes a GPS signal reception section 201, a payload data generation section 202, an ID/CRC addition section 203, an FEC processing section 204, a repetition section 205, a guard bit addition section 206, a key stream generation section 211, an and gate 212, an exclusive or a gate 213, a Gold code generation unit 214, an exclusive or gate 215, a synchronization generation unit 221, an interleaving unit 222, a modulation unit 223, and a frequency/timing control unit 224. In some embodiments, only a single or selected number of elements 206 and 224 may be provided and may be referred to generally as a delivery portion.

The GPS signal receiving unit 201 receives a GPS signal, acquires a 1PPS (pulse/second) signal and the current time (GPS time) included in the GPS signal, and supplies it as a clock signal to the frequency/timing control unit 224. In addition, the GPS signal receiving unit 201 acquires position information (latitude, longitude, altitude) of the transmitting device 101 from the GPS signal, and supplies the position to the payload data generating unit 202 as sensed sensor information.

The payload data generation unit 202 generates payload data as a payload of a radio signal from position information as sensor information from the GPS signal reception unit 201, and supplies the payload data to the ID/CRC attachment unit 203. It should be noted that the information as payload data is not limited to the position information, but also includes sensor information. The information as payload data may be determined according to, for example, an application to which the wireless system is applied, or the like. However, the new communication method is a new communication method for LPWA communication, which is capable of transmitting information in a wide range of several tens to 100km with low power consumption, and the size of information used as payload data is suitable for LPWA communication, desirably having a certain size.

ID/CRC attachment section 203 adds an ID (identification information) and a CRC (cyclic redundancy check) code of transmission apparatus 101 to the payload data from payload data generation section 202, thereby performs FEC (forward error correction), generates an FEC target unit to be processed, and supplies it to FEC processing section 204. ID/CRC adding section 203 generates a CRC code of the payload data or the payload data and the ID.

An FEC processing unit (also referred to as an FEC encoder) 204 performs FEC processing on the FEC target unit from the ID/CRC attachment unit 203, and supplies the FEC frame obtained as a result to a repetition unit 205. That is, the FEC processing unit 204 performs error correction coding of the FEC target unit as FEC processing of the FEC target unit, and supplies an error correction code obtained by the error correction coding to the repeating unit 205. Specifically, in the embodiment, the FEC processing unit 204 performs, for example, LDPC encoding of the FEC target unit, and supplies the LDPC code obtained by the LDPC encoding to the repeating unit 205. It should be noted that the error correction code is not limited to the LDPC code. As the error correction code, for example, a convolutional code, a turbo code, or the like can be employed.

The repetition unit 205 (also referred to as a frame formation section or including a frame formation section) generates a repetition unit in which the LDPC code from the FEC processing unit 204 is repeatedly arranged, and supplies it to the guard bit addition unit 206. The repeating unit 205 employs aspects of the present disclosure and will be explained in more detail below.

The guard bit adding section 206 adds (inserts) a guard bit from the repeating unit 205 to the repeating unit, and supplies it to the exclusive or gate 213.

The key stream generation unit 211 generates a key stream to be used for encryption, and supplies it to the and gate 212. In addition to the key stream from the key stream generation unit 211, a switching signal for switching validity/invalidity of encryption in the exclusive or gate 213 is supplied to the and gate 212.

The switching signal is, for example, a logic 1 (e.g., high level) in the case where encryption is enabled, and a logic 0 (e.g., low level) in the case where encryption is disabled. For example, the switching signal may be set according to the application. The switching signal may be set such that the entire repeating unit or a part of the repeating unit supplied from the protection bit adding unit 206 to the xor gate 213 is effectively encrypted. Further, the switching signal may be set so that the entire encryption of the repeating unit supplied from the protection bit adding unit 206 to the xor gate 213 is invalid.

And gate 212 calculates the logical product of the switching signal and the keystream from keystream generation unit 211 and supplies it to xor gate 213. As a result, the keystream is provided from and gate 212 to xor gate 213 only during the period in which encryption is active in the switching signal.

Exclusive or gate 213 encrypts the repeated unit with a stream cipher (method) by calculating the exclusive or of the repeated unit from protection bit adding section 206 and the key stream from and gate 212. Xor gate 213 supplies the encrypted repeat units to xor gate 215. Here, in the exclusive or gate 213, a period during which the key stream from the and gate 212 is supplied (i.e., a period during which the switching signal is at logic 1) is encrypted. Thus, in the xor gate 213, all or a portion of the repeating unit may be encrypted, or the entire repeating unit may not be encrypted. For example, the Gold code generating unit 214 generates, for example, a Gold code as a scrambling sequence of the same size (number of bits) as that of the repeating unit from the exclusive or gate 213 using two M sequence generators and the exclusive or gate 215. The xor gate 215 scrambles the repeated units by calculating the xor of the repeated units from the xor gate 213 and the scrambling sequence from the Gold code generating unit 214, and supplies it to the interleaving unit 222.

The synchronization generating unit 221 generates a predetermined PN (pseudo noise) sequence such as an M sequence, for example, as a synchronization signal, and supplies it to the interleaving unit 222. It should be noted that the synchronization signal generated by the synchronization generation unit 221 is a signal known to the transmission apparatus 101 and the reception apparatus 112. Since the synchronization signal is known to the transmitting apparatus 101 and the receiving apparatus 112, the receiving apparatus 112 can perform synchronization detection of the radio signal from the transmitting apparatus 101, and can perform robust reception of the radio signal from the transmitting apparatus 101. The initial value of the M-sequence may be any value as long as it is a common value for transmission and reception. The initial value of the M-sequence may also be changed according to the ID.

The interleaving section 222 performs the bit sequences d (0), d (1) … … as a repeating unit from the exclusive or gate 213 and the bit sequences r (0), r (1) … … and the interleaving sequences r (0), d (0), r (1), d (1) … … or r0(0), d (832), r (1), d (1) … … to the modulation section 223.

The modulation unit 223 performs modulation, such as pi/2 shift BPSK (pi/2 shift binary phase shift keying) modulation and linear modulation, using, for example, an interleaving sequence (e.g., 920MHz band radio signal as the modulation signal obtained by the above-described method) supplied from the interleaving unit 222. Note that the modulation unit 223 transmits a radio signal at the transmission timing and the transmission frequency according to the control from the frequency/timing control unit 224.

The frequency/timing control unit 224 sets the transmission timing and the transmission frequency of the wireless signal transmitted by the modulation unit 223 according to the ID of the transmission device 101 or the like, and transmits the wireless signal at the transmission timing and the transmission frequency, and controls the modulation unit 223. The frequency/timing control unit 224 controls the modulation unit 223 in synchronization with the clock signal from the GPS signal receiving unit 201. That is, according to the clock signal from the GPS signal reception unit 201, for example, the frequency/timing control unit 224 determines whether the current timing is a grid (predetermined timing) known in the transmission device 101 and the reception device 112. The frequency/timing control unit recognizes whether the current timing is a timing (grid time), and controls the modulation unit 223 so as to start transmission of a packet at the grid timing.

Fig. 8 is a block diagram showing a configuration example of the reception apparatus 112. The receiving apparatus 112 includes a GPS signal receiving unit 231 (or generally a receiving section), an ID/transmission mode acquisition unit 232, a frequency/timing control unit 233, a demodulation unit 234 (representing and/or including a frame extraction section), and a decoding unit 235 (representing an FEC decoder).

The GPS signal receiving unit 231 receives the GPS signal, acquires a 1PPS (pulse/second) signal and GPS time included in the GPS signal, and supplies it as a clock signal to the frequency/timing control unit 233. For example, the ID/transmission mode acquisition unit 232 acquires, from the cloud server 103, a transmission mode that is a mode in which the receiving apparatus 112 receives the ID, the transmission timing, and the transmission frequency of the transmitting apparatus 101 that is the reception target of the radio signal from the timing control unit 233.

The frequency/timing control unit 233 sets the reception timing and the reception frequency of the radio signal in the demodulation unit 234 according to the transmission mode from the ID/transmission mode acquisition unit 232, and receives the radio signal at the reception timing and the reception frequency, thereby controlling the demodulation unit 234. The frequency/timing control unit 233 controls the demodulation unit 234 in synchronization with the clock signal from the GPS signal reception unit 231, as with the frequency timing control unit 224 in fig. 7.

As described above, the transmission timing and transmission frequency control of the modulation section 223 (fig. 7) and the reception timing and reception frequency control of the demodulation section 234 are each controlled by the clock signal obtained from the GPS signal, and by synchronizing with the time information, the transmission timing and transmission frequency of the modulation section 223 can be accurately matched with the reception timing and reception frequency of the demodulation section 234.

The demodulation unit 234 receives the radio signal from the transmission apparatus 101 at the reception timing and the reception frequency according to the control of the frequency/timing control unit 233, performs FFT (fast fourier transform) or the like of the radio signal, and demodulates the radio signal. The demodulation unit 234 supplies a demodulation signal obtained by demodulating the radio signal to the decoding unit 235. In the demodulation of the decoding unit 234, for example, synchronization detection using a synchronization signal is performed, and also the combination described in fig. 2 is performed.

The decoding unit 235 performs error correction by decoding the LDPC code included in the decoded signal from the demodulation unit 234, and outputs sensor information included in the payload data obtained as a result. The sensor information is transmitted from the reception device 112 to the cloud server 103.

Fig. 9 is a diagram showing an example of data (signal) in the first format processed by the transmitting apparatus 101. Here, in the new communication method, for example, the modulation rates (transmission rates) performed in the modulation section 223 are 6.35kbps and 50.8 kbps. Fig. 9 shows the data format when the modulation rate is 6.35kbps of 6.35kbps and 50.8 kbps.

In the new communication method, for example, three types of modes (i.e., MSDU type 1, MSDU type 2, and MSDU type 3) are prepared as payload data setting modes. The payload data is for example a 128 bit unit called MSDU (MAC (medium access control) service data unit). In the case of MSDU type 1, MSDU type 2, MSDU type 3, the actual data length is 128 bits, 64 bits or 1 bit, respectively. It is used to transmit data (user data). That is, in MSDU type 1, the payload data generation unit 202 constructs (generates) a 128-bit MSDU service data unit using 128-bit actual data (sensor information and the like) as it is. In MSDU type 2, the payload data generation unit 202 pads 64-bit actual data with 64-bit 0's to form a 128-bit MSDU. In MSDU type 3, the payload data generation unit 202 pads 1-bit actual data with 127-bit 0's to form a 128-bit MSDU.

MSDU type depends on the application. For example, the sending of positioning data may require 128 bits (type 1), while other sensors may send only less information. For binary sensor data (on/off, true/false), for example for early seismic detectors, one data bit is sufficient (type 3). In general, the actual data length may be any number less than or equal to a predetermined maximum value (e.g., up to 128 bits). The MSDU type index is stored on the cloud server, for example, along with the device id (userid), so that the receiver knows the actual data length.

In the 128-bit MSDU, the 32-bit ID and the 24-bit CRC code of the transmitter 101 are added in the ID/CRC attachment section 203 with a PSDU (physical layer service unit) as an FEC target unit, and it becomes a 184-bit unit.

In the FEC processing unit 204, for example, 184-bit PSDU is encoded into an LDPC code having a code length N of 736 bits and a coding rate r of 1/4, resulting in an LDPC code (coded bits) of 736 bits (184 × 4/1).

In the first format with a modulation rate of 6.35kbps, the 736-bit LDPC code is repeated twice, and further, 184-bit portions of the 736-bit LDPC code are repeated to generate a 1656-bit (736 bits × 2+184 bits) repetition unit. That is, in the first format, the repetition unit is configured by repeatedly arranging the 736-bit LDPC code twice and further arranging the 184-bit part of the 736-bit LDPC code.

As the 184-bit portion of the 736-bit LDPC code arranged in the repetition unit, for example, the first 184 bits of the 736-bit LDPC code can be employed. Further, according to the present disclosure, a 184-bit portion of the 736-bit LDPC code arranged in the repetition unit may be selected according to a predetermined optimization mode. The guard bit adding unit 206 adds (inserts) a guard bit to the repeating unit. That is, 4-bit guard bits (G) are added to each of the head and end of the repeating unit. By adding a guard bit, the 1656-bit repeat unit becomes a 1664-bit (1656-bit + 4-bit × 2) repeat unit. As the 4-bit guard bit, all 0 bits or a counter indicating a frame number may be employed.

Here, in the FFT in the repetition section performed in demodulation section 234 (fig. 8) of reception apparatus 112, the signal quality at the end of the repetition section deteriorates. As a countermeasure against deterioration of the signal quality, guard bits are added to the head and the end of the repeating unit, respectively. For the repeating unit, the xor gate 213 calculates an xor with the key stream, so that the repeating unit becomes an encrypted stream.

Here, when the set mode of the payload data is MSDU type 2 or MSDU type 3, a part of 128-bit MSDU as the payload data is padded with 0. Since MSDU type 2 pads 64 bits of actual data with 64 bits of 0, half of a 128 bit MSDU is 0. In other words, half of the MSDUs are meaningless information. In MSDU type 3, most of the 128-bit MSDU is meaningless information since 1-bit actual data is padded with 127-bit 0's.

In the new communication method, in the case where there is much such meaningless information (in the case of MSDU type 2 or MSDU type 3), configuration is made such that the wireless energy transmitted to the communication path can be utilized efficiently to the maximum extent. That is, in the new communication method, data (part or all) generated by padding 0 cannot be encrypted. When the padding 0 is not encrypted, a switching signal is supplied to the and gate 212 for invalidating the encryption of the padding period 0 in the repeating unit. In response to the switching signal, the and gate 212 supplies the key stream to the xor gate 213, whereby in the xor gate 213, the xor gate 213 generates the key stream in a period in which encryption is not invalid (i.e., a period in which encryption is valid). The repeating units are encrypted using the keystream from and gate 212 as a target. In the portion where encryption is invalid, the padding 0 data is output as it is without encryption. The encrypted portion known to be invalid in this way is data 0 in the receiving apparatus 112. Therefore, in the demodulation unit 234 of the reception apparatus 112, the synchronization performance can be improved by regarding the signal of the encryption invalid portion as the synchronization signal. Also, in the demodulation section 235, the error correction performance can be improved by decoding the portion in which the encryption is invalid as the known data "0". That is, by partially invalidating the encryption for a short time in the payload, the performance of the receiving apparatus 112 is improved. With this performance improvement, for example, equivalent communication performance can be achieved even at a lower transmit antenna power.

The encrypted stream consists of 1664 bits as with the repeat unit before encryption. The 1664 bit encrypted stream is scrambled by the xor gate 215 by xor with the gold code as the scrambling sequence and becomes a scrambled stream. Similar to the cipher stream before scrambling, the scrambled stream is a 1664 bit sequence d (0), d (1) … … d (1663).

For the first format with a modulation rate of 6.35kbps, the synchronization generation unit 221 generates the bit sequences r (0), r (1) … … r (831) as the 832-bit synchronization signal (Sync). Thus, for the first format with a modulation rate of 6.35kbps, the ratio of the length of the synchronization signal to the length of the scrambled stream is 832:1664 to 1: 2.

The bit sequences r (0), r (1) … … r (831) as the 832-bit synchronization signal and the bit sequences d (0), d (1) … … d (1663) as the 1664-bit scrambled streams are interleaved in the interleaving section 222. As a result, bit sequences r (0), d (832), r (1), d (0), d (2), etc. are generated as 2496-bit PPDUs (representing protocol data units) (1), d (833) … ….

Here, for example, bit sequences r (0), r (1) … … r (831) and bit sequences d (0), d (1) as 832-bit synchronization signals are interleaved as 1664- … … d (1663) according to the following C procedure. Note that PPDU (n) denotes the (n +1) th bit from the head of the 2496-bit PPDU, and (n% x) denotes a remainder obtained by dividing n by x. The symbol "means" whether or not the calculation results are equal. Further, in a division calculation (n/3, etc.), where n is the dividend, the decimals below the decimal point are rounded off:

for the 2496-bit PPDU, pi/2 shift BPSK modulation of 6.35kbps is performed by the modulator 223, and further linear modulation of 400kHz/s is performed. Then, 2496-bit PPDU is transmitted as a radio signal.

For a 2496 bit PPDU, the transmission (transit) time of the 2496 bit PPDU is approximately 393.2ms when applying pi/2 shifted BPSK modulation of 6.35 kbps. This is transmission of 0.4 seconds or less and satisfies the ARIB rule of the 920MHz band.

For linear modulation (chirp modulation), for example, a frequency shift of about-78.6 kHz is given at the beginning of the transmission of a PPDU, which has a transmission time of about 393.2 ms. For a linear modulation of 400kHz/s, the frequency varies linearly at a rate of change of 400kHz/s, so the frequency shift at the end of a PPDU transmission with a transmission time of about 393.2ms is about +78.6 kHz. For example, when the frequency (center frequency) of the carrier wave is 925Mhz, the signal frequency of the radio signal changes linearly from 924.9214Mhz to 925.0786Mhz by linear modulation. With this linear modulation, even if a modulation rate of 6.35Kbps is used, since the frequency utilization efficiency is improved, the interference resistance becomes strong, and the amount of calculation involved in the synchronization detection due to the characteristics of the linear modulation can also be reduced.

For the first format, the transmitting apparatus 101 repeatedly (e.g., four times) transmits PPDUs as packets. In this case, the time required for four transmissions of a PPDU is about 1.57 seconds (393.2 ms × 4).

In the present embodiment, one type of LDPC code having an encoding length N of 736 bits and an encoding rate r of 1/4 is prepared as an LDPC code, and the setting modes of payload data are MSDU type 1, MSDU type 2, and MSDU type 3, padding 0 constitutes 184-bit PSDU as an FEC target unit, LDPC encoding of 184-bit PSDU is classified into one type of LDPC code for each setting mode, prepared for each setting mode, and LDPC encoding of actual data in each setting mode is performed without padding 0, for example, and LDPC encoding can be performed using the LDPC code for the setting mode.

However, in preparing the LDPC code for each setting mode, the transmission apparatus 101 needs to store the check matrix of the LDPC code for each setting mode, and in the LDPC encoding, processing such as switching the matrix is required. On the other hand, when one type of LDPC code having a code length N of 736 bits and a code rate r of 1/4 is used in the transmission apparatus 101, for the LDPC code, a check matrix of one type of LDPC code is stored and it is not necessary to switch the check matrix, so that it is possible to reduce the load and thus reduce the power consumption.

Fig. 10 is a diagram showing an example of data in the second format processed by the transmitting apparatus 101. That is, fig. 10 shows the data format when the modulation rate is 50.8kbps of 6.35kbps and 50.8 kbps.

In the second format, MSDU as payload data, PSDU as FEC target unit, and LDPC encoding are the same as those in the case of the first format (fig. 9), and thus description is omitted. In the second format having a modulation rate of 50.8kbps, the 736-bit LDPC code is repeated six times, and further, 384 bits of the 736-bit LDPC code are repeated to generate a 4800-bit (736 bits × 6+384 bits) repeating unit. That is, in the second format, the repetition unit is configured by repeatedly arranging the 736-bit LDPC code six times and further arranging the 384-bit part of the 736-bit LDPC code.

As a 384-bit portion of the 736-bit LDPC code arranged in the repeating unit, for example, the first 384 bits of the 736-bit LDPC code may be employed. Further, according to the present disclosure, 384-bit portions of 736-bit LDPC codes arranged in a repeating unit may be selected according to a predetermined optimization mode.

For the repeating unit, as in the case of the first format, 4-bit guard bits (G) are added to the header and the end, respectively. By adding the guard bit, the 4800-bit repeating unit becomes a 4808-bit (4800-bit + 4-bit × 2) repeating unit. Thereafter, in the second format, as in the case of the first format, the 4808-bit repetition unit is encrypted into an encrypted stream, further scrambled, and made into a scrambled stream. In the second format, the scrambled stream is a 4808 bit sequence of bits d (0), d (1) … … d (4807) of the same size as the repeat unit to which the guard bits are appended.

For the second format, the synchronization generation unit 221 generates the bit sequences r (0), r (1) … … r (0) … … r (0) as a 4808-bit synchronization signal (Sync) of the same size as the scrambled stream 4087. Thus, for the second format, the ratio of the length of the synchronization signal to the length of the scrambled stream is 4808:4808 to 1: 1.

The bit sequences r (0), r (1) … … r (4807), which are 4808-bit synchronization signals, and the bit sequences d (0), d (1) … …, and d (4807), which are 4808-bit scrambled streams, are interleaved by the interleaving section 222. As a result, bit sequences r (0), d (0), r (1), d (1), and d (0) of the PPDU, which are 9616 bits (4808 bits +4808 bits), are generated, wherein bits, which are synchronization signals, are periodically inserted. Here, the bit sequences r (0), r (1) … … r (4807) as the 4808-bit sync signal and the bit sequences d (0), d (1) … … d (4807) as the 4808-bit scrambled stream are interleaved according to the following C procedure, for example:

for the 9616-bit PPDU, pi/2 shift BPSK modulation of 50.8kbps is performed by the modulation unit 223 and transmitted as a radio signal. When pi/2 shift BPSK modulation of 50.8kbps is applied to the 9616-bit PPDU, the transmission time of the 9616-bit PPDU is about 189.4 ms. Since it is less than 0.2 second specified by ARIB, it can be repeatedly transmitted a plurality of times with a short transmission pause time.

With respect to the second format, the transmitting apparatus 101 repeatedly transmits PPDUs as packets, for example, 20 times. In this case, the time required to transmit 20 PPDUs is about 3.78 seconds (═ 189.4ms × 20). In the second format, since the number of repetitions is large, information can be transmitted more reliably even if there is an influence such as fading.

The selection of the first format and the second format has different attenuation characteristics or the like as required by the application and may therefore be selected by the application.

In fig. 11, the key stream generating unit 211 includes a key generating unit 251, a Nonce (Nonce) generating unit 252, a block encrypting unit 253, and a P/S converting unit 254. The key stream generation unit 211 generates a key stream for encryption. The keystream generation unit 211 generates a 1664 bit keystream for the first format and a 4808 bit keystream for the second format.

The key generation unit 251 generates 128-bit key information. As for the key generation unit 251, the internal structure is not disclosed, and the security of encryption is ensured. As for the key generation unit 251, the configuration thereof may be any configuration as long as the internal configuration is not easily guessed. For example, the key generation unit 251 may obtain (generate) the key information by acquiring the GPS time from the GPS signal reception unit 201 (fig. 7) and adding zero data so that the number of bits becomes 128 bits. The key generation unit 251 supplies the generated key information to the block encryption unit 253.

The temporary value generation unit 252 generates a 128-bit temporary value (a number used once). For a temporary value, it is expected that the value will be different each time the bit clock is divided by 128. For example, the temporary value generation unit 252 may be constituted by a 128-bit counter. In this case, for example, the temporary value generation unit 252 initializes the counter to a predetermined count value before starting transmission of the wireless signal, and then increments the count value by 1 at each timing of the bit clock division by 128. Thereby, a temporary value can be generated. The temporary value generation unit 252 supplies the generated temporary value to the block encryption unit 253.

The block encryption unit 253 generates a 128-bit block cipher using the key information from the key generation unit 251 and the nonce value from the nonce value generation unit 252, and supplies the block cipher to the P/S conversion unit 254. As the block cipher, for example, an AES (advanced encryption standard) code, a CLEFIA code, or the like can be used.

The P/S converter 164P/S (parallel to serial) converts the block cipher in units of 128 bits from the block encryption unit 253 in units of 1 bit to generate a serial key stream (1 bit unit), and supplies it to the and gate 212. For the first format, the P/S converter 164 generates a 1664 bit keystream, and for the second format, a 4808 bit keystream.

According to the present disclosure, the FEC encoder 204 is configured to encode the payload data into FEC codewords 300, 400 (see fig. 9 and 10), each FEC codeword having a predetermined codeword length. The frame forming part (represented by or comprised in the repeating unit 205) is configured to form

frames

310, 410 having a predetermined frame length. Then, the

transport stream

320, 420 is formed of a plurality of

frames

310, 410 formed by the frame forming part. This will be explained in more detail below.

Frame 310 is shown separately in fig. 12 and frame 410 is shown separately in fig. 13. As shown in these figures, the

frame

310, 410 comprises a

first frame portion

311, 411 having a first predetermined length which is an integer multiple of the predetermined codeword length, and a

second frame portion

312, 412 having a second predetermined length which is shorter than the predetermined codeword length. In addition, in the exemplary embodiment,

third frame portions

313, 413 and

fourth frame portions

314, 414, respectively including guard bits, are provided; however, in other embodiments, no such third and fourth frame portions, or one or more other frame portions, are provided in addition to the first and second frame portions. The guard bits may, for example, provide information about the frame number within the superframe, e.g., the guard bits are 0000 for the first frame, 0001 for the second frame, and so on (repeated at both the beginning and end of frames 310, 410).

Frame 310 is preferably used for format 1(6.35K linear (Chirp)) of fig. 9, while frame 410 is preferably used for format 2(50.8K DSSS) of fig. 10. The 50.8K mode uses 8 times larger bandwidth, which will produce 8 times more noise power in an Additive White Gaussian Noise (AWGN) channel. Thus, more FEC codeword 400 repetitions are used (6 times) than only 2 FEC codeword repetitions in the case of format 1. One way to fully compensate for the large noise level in the case of format 2 is to use the FEC codeword 400 exactly more than 8 times. Another way is to only partially increase the number of FEC codewords and further increase the number of frames 410 transmitted in addition.

The frame formation part is further configured to include the

FEC codeword

300, 400 and a predetermined number of repetitions of said

FEC codeword

300, 400 into a

first frame portion

311, 411 of a frame, and to include a selected number of bits of said

FEC codeword

300, 400 into a

second frame portion

312, 412 of said frame. As shown in fig. 12, the first frame portion 311 includes two repetitions of the codeword 300. As shown in fig. 13, the first frame portion 411 includes two repetitions of the codeword 400.

Fig. 14 and 15 show the

code words

300 and 400, respectively, and various options for a portion of the

code words

300, 400 to be included in the

second frame portions

312, 412. In these exemplary embodiments, the

code words

300, 400 are code words of systematic codes, in particular LDPC codes, and as shown in fig. 14A and 15A, include

information portions

315, 415 of 184 information bits and

parity portions

316, 415 of 552 parity bits for a total of 736 code bits. However, in other embodiments, other codes and other numbers of bits may be applied.

Fig. 14B-14H show seven different options for including a portion of the codeword 300 in the second frame portion 312 of the frame 310. These parts are indicated in the figures with individual hatching. In this embodiment (referring to the embodiment shown in fig. 9 and 12), the second frame portion 312 includes 184 bits.

According to the first pattern shown in fig. 14B, referred to as pattern 0, only information bits, in particular the complete information portion 315, are included in the second frame portion 312. This results in a more intense protection of these information bits.

The FEC code may be an example of a Low Density Parity Check (LDPC) code with an optimized degree spectrum to allow decoding at very low SNR. In a preferred embodiment, the LDPC code is systematic and dual diagonals are used in the parity check portion of the parity check matrix (i.e., systematic codes and parity codes will be accumulated). This results in a parity check with a degree of variability of 2 (only 2 output edges (i.e., connections) check the node). This affects 551 parity out of 552 parity bits. The last parity bit is only 1 degree. However, the information bits are used in larger degrees, e.g. 10 degrees, 9 degrees and partly 3 degrees. The overall degree spectrum is affected by code optimization. It should be noted that code bits with small variable node degrees collect only a limited amount of information during message passing decoding by the FEC decoder. Therefore, parity checks that repeat LDPC codewords are beneficial because they have a smaller degree of variable nodes.

According to the second mode (referred to as mode 1) shown in fig. 14C, only parity bits (in particular, the 184 least significant parity bits (defined as the rightmost bit of the bit sequence) 317 of the parity portion 316) are included in the second frame portion 312. This provides stronger protection against weak parity, thereby improving code convergence, and is easy to implement. However, the stronger parity bits are very locally clustered in the FEC codeword and may not allow the FEC decoder to converge to a low bit error rate.

According to the third and fourth patterns (referred to as patterns 2 and 3) shown in fig. 14D and 14E, uniformly distributed code bits 318 (including information bits and parity bits) among all code bits of the code word 300 are contained in the second frame portion 312. This provides for distributing the individually protected bits evenly over the complete codeword, which may be beneficial for codes with Equal Error Protection (EEP) in all code bits. In a preferred embodiment, an irregular LDPC code is used, where the code bits have Unequal Error Protection (UEP), the first code bit being more robust than the last (parity) bit.

According to the fifth, sixth and seventh patterns (referred to as patterns 4, 5 and 6) shown in fig. 14F, 14G, 14H, only parity bits are contained in the second frame portion 312, in particular parity bits 318 evenly distributed over the parity portion 316. This results in a more robust protection of these parity bits 319. It should be noted that for modes 5 and 6, only the triple parity bit 320 is shown to indicate a different way of evenly distributing the parity bits 319 to be protected. These patterns (4, 5 and 6) are easy to implement (conventional structure) and allow for evenly distributed parity repetition. This results in overall optimal FEC decoding performance.

Fig. 15B-15H show seven different options for including a portion of the codeword 400 in the second frame portion 412 of the frame 410. These parts are indicated in the figures with individual hatching. In this embodiment (referring to the embodiment shown in fig. 10 and 13), the second frame portion 412 includes 384 bits.

According to the first pattern shown in fig. 15B, referred to as pattern 0, in particular, the complete information part 415 is contained in the second frame part 412, as well as the most significant (defined as the leftmost bit of the bit sequence) (200) parity bits 423. This results in a more intense protection of these information bits.

According to the second mode (referred to as mode 1) shown in fig. 15C, only parity bits (in particular, the 352 least significant parity bits (defined as the rightmost bit of the bit sequence) 417 of the parity portion 416) are included in the second frame portion 412. This makes the weak parity more strongly protected and thus improves code convergence.

According to the third and fourth patterns (referred to as patterns 2 and 3) shown in fig. 15D and 15E, uniformly distributed code bits 418 (including information bits and parity bits) among all code bits of the code word 400 are contained in the second frame portion 412. Further, a longer portion 421 (here 32) of code bits from the beginning or end of the code word 400 is contained in the second frame portion 412. This provides individually protected bits and the longer portions 421 are evenly distributed over the complete codeword, with a 32-bit block being repeated, with a few exceptions at the beginning and end of the codeword.

According to the fifth, sixth and seventh patterns (referred to as patterns 4, 5 and 6) shown in fig. 15F, 15G, 15H, only parity bits, in particular parity bits 419 evenly distributed over the parity portion 416, are contained in the second frame portion 412. Further, also in these embodiments, a longer portion 422 (here 48) of the parity bits from the end of the parity portion 416 is contained in the second frame portion 412. This results in a more robust protection of these

parity bits

419 and 422. It should be noted that for modes 5 and 6, only the triple parity bits 420 are shown to indicate different ways of evenly distributing the parity bits 419 to be protected.

According to the eighth pattern shown in fig. 15I (referred to as pattern 7), 384 repeated bits 424 are evenly distributed over the parity portion 416 in a completely regular pattern (referred to as pattern _23) without repeating large blocks toward the end of the codeword (as in patterns 4, 5, and 6). This is easy to implement (conventional structure) and allows for evenly distributed parity repetition. This results in overall optimal FEC decoding performance.

A receiving apparatus according to the present disclosure generally includes a frame extraction section configured to extract one or more frames from a received transport stream, the frames including payload data encoded into FEC codewords each having a predetermined codeword length, and the frames having a predetermined frame length. As explained above, the frame comprises a first frame portion having a first predetermined length which is an integer multiple of the predetermined codeword length, and a second frame portion having a second predetermined length which is shorter than the predetermined codeword length. The frame extraction section is further configured to extract an FEC codeword and a predetermined number of repetitions of the FEC codeword from a first frame portion of a frame, and to extract a selected number of bits of the FEC codeword from a second frame portion of the frame. Further, an FEC decoder is provided, configured to decode payload data from the FEC codewords extracted from the frame, the repetitions of the FEC codewords, and the selected number of bits of the FEC codewords.

With the disclosed apparatus and method using repeated code bits in the second frame portion, improvements in SNR and coding gain may be achieved. In addition to the code words in the first frame portion, the code bits in the second frame portion are used by the FEC decoder by accumulating the soft values of the decoded bits in order to increase the signal level, thereby improving coding gain and SNR.

Accordingly, the foregoing discussion discloses and describes merely exemplary embodiments of the present disclosure. As will be understood by those skilled in the art, the present disclosure may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosure of the present disclosure is intended to be illustrative, but not limiting, of the scope of the disclosure and other claims. The present disclosure, including any readily discernible variants of the teachings herein, defines, in part, the scope of the foregoing claim terminology such that no inventive subject matter is dedicated to the public.

In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

In embodiments that have been described so far as being implemented (at least in part) by software-controlled data processing apparatus, it should be understood that non-transitory machine-readable media, such as optical disks, magnetic disks, semiconductor memory, etc., carrying such software, are also considered to represent embodiments of the present disclosure. Further, such software may also be distributed in other forms, such as via the internet or other wired or wireless telecommunication systems.

Elements of the disclosed apparatus, devices, and systems may be implemented by corresponding hardware and/or software elements, such as appropriate circuitry. A circuit is a structural combination of electronic components including conventional circuit elements, including application specific integrated circuits, standard integrated circuits, application specific standard products, and field programmable gate arrays. Further, the circuitry includes a central processing unit, a graphics processing unit, and a microprocessor programmed or configured according to software code. Although the circuitry includes software executed by the hardware described above, the circuitry does not include pure software.

The following is a list of other embodiments of the disclosed subject matter:

1. a transmitting device, in particular for low throughput networks, comprising:

an FEC encoder configured to encode the payload data into FEC codewords each having a predetermined codeword length,

2. According to the transmission apparatus described in the embodiment 1,

wherein the frame formation section is configured to include only parity bits of an FEC codeword into a second frame portion of the frame.

3. According to the transmission apparatus described in the embodiment 2,

wherein the frame formation is configured to include all parity bits of an FEC codeword or a least significant portion of the parity bits into a second frame portion of the frame.

4. According to the transmission apparatus described in the embodiment 2,

wherein the frame formation is configured to include evenly distributed parity bits of all parity bits of an FEC codeword into the second frame portion of the frame.

5. According to the transmission apparatus described in the embodiment 1,

wherein the frame formation section is configured to include only information bits of an FEC codeword into a second frame portion of the frame.

6. According to the transmission apparatus described in the embodiment 5,

wherein the frame formation is configured to include all information bits of an FEC codeword or a least significant portion of the information bits into a second frame portion of the frame.

7. According to the transmission apparatus described in the embodiment 1,

wherein the frame formation section is configured to evenly distribute code bits among all code bits of an FEC codeword into a second frame portion of the frame.

8. According to the transmission apparatus described in the embodiment 1,

wherein the frame formation is configured to include all information bits and part of the parity bits of an FEC codeword into a second frame portion of the frame.

9. The transmitting apparatus according to any one of the preceding embodiments,

wherein the FEC encoder is configured to encode the payload data into FEC codewords of a systematic code.

10. The transmitting apparatus according to any one of the preceding embodiments,

further comprising a transmitting section configured to form a transport stream from the plurality of frames formed by the frame forming section.

11. According to the transmission apparatus described in the embodiment 10,

wherein the transmitting section includes a modulating section configured to modulate data contained in a frame using linear modulation or direct sequence spread spectrum modulation.

12. According to the transmission apparatus described in the embodiment 10,

wherein the transmitting part includes an encrypting part for encrypting data contained in the frame, a scrambling part for scrambling data contained in the frame, and/or an interleaving part for interleaving data contained in the frame.

13. A transmission method, in particular for low throughput networks, comprising:

-encoding the payload data into FEC codewords each having a predetermined codeword length,

-forming a frame having a predetermined frame length, wherein a frame comprises a first frame portion having a first predetermined length being an integer multiple of the predetermined codeword length and a second frame portion having a second predetermined length being shorter than the predetermined codeword length by including FEC codewords and a predetermined number of repetitions of said FEC codewords into the first frame portion of the frame and by including a selected number of bits of said FEC codewords into the second frame portion of said frame.

14. A receiving apparatus, in particular for a low throughput network, comprising:

-a frame extraction section configured to extract one or more frames from the received transport stream, a frame comprising payload data encoded as FEC codewords having respective predetermined codeword lengths and having a predetermined frame length, wherein a frame comprises a first frame portion having a first predetermined length being an integer multiple of the predetermined codeword length and a second frame portion having a second predetermined length being shorter than the predetermined codeword length, wherein the frame extraction section is configured to extract the FEC codewords and a predetermined number of repetitions of the FEC codewords from the first frame portion of the frame and to extract a selected number of bits of the FEC codewords from the second frame portion of the frame, and

15. According to the receiving apparatus as set forth in embodiment 14,

further comprising a receiving section configured to receive a transport stream formed of a plurality of frames including payload data encoded into FEC codewords each having a predetermined codeword length.

16. A receiving method, in particular for a low throughput network, comprising:

-extracting one or more frames from the received transport stream, a frame comprising payload data encoded as FEC codewords having respectively a predetermined codeword length and a frame having a predetermined frame length, wherein a frame comprises a first frame portion having a first predetermined length being an integer multiple of the predetermined codeword length and a second frame portion having a second predetermined length being shorter than the predetermined codeword length by extracting from a first frame portion of the frame a FEC codeword and a predetermined number of repetitions of said FEC codeword and by extracting from a second frame portion of said frame a selected number of bits of said FEC codeword, and

-decoding payload data from the FEC codewords extracted from the frame, the repetitions of the FEC codewords, and the selected number of bits of the FEC codewords.

17. A non-transitory computer-readable recording medium having stored therein a computer program product which, when executed by a processor, causes the method according to 13 or 16 to be performed.

18. Computer program comprising program code means for causing a computer to carry out the steps of the method according to embodiment 13 or 16 when said computer program is carried out on a computer.

Claims

1. A transmitting apparatus for a low throughput network, the transmitting apparatus comprising:

an FEC encoder configured to encode the payload data into FEC codewords having predetermined codeword lengths, respectively, an

A frame formation section configured to form a frame having a predetermined frame length, wherein a frame comprises a first frame portion having a first predetermined length that is an integer multiple of the predetermined codeword length, and a second frame portion having a second predetermined length that is shorter than the predetermined codeword length, wherein the frame formation section is configured to include an FEC codeword and a predetermined number of repetitions of the FEC codeword into the first frame portion of a frame, and to include a selected number of bits of the FEC codeword into the second frame portion of the frame;

wherein the frame formation section is configured to include uniformly distributed parity bits of all parity bits of the FEC codeword into the second frame portion of the frame or to include uniformly distributed code bits of all code bits of the FEC codeword into the second frame portion of the frame.

2. The transmission apparatus according to claim 1, wherein,

wherein the frame formation section is configured to include only parity bits of the FEC codeword into the second frame portion of the frame.

3. The transmission apparatus according to claim 1, wherein,

wherein the frame formation section is configured to include only information bits of the FEC codeword into the second frame portion of the frame.

4. The transmitting device of any one of the preceding claims,

5. A transmission method for a low throughput network, the transmission method comprising:

the payload data is encoded into FEC codewords each having a predetermined codeword length,

forming a frame having a predetermined frame length, wherein a frame comprises a first frame portion having a first predetermined length which is an integer multiple of said predetermined codeword length and a second frame portion having a second predetermined length which is shorter than said predetermined codeword length by including FEC codewords and a predetermined number of repetitions of said FEC codewords into said first frame portion and by including a selected number of bits of said FEC codewords into said second frame portion of said frame;

wherein forming the frame is configured to include evenly distributed parity bits of all parity bits of the FEC codeword or evenly distributed code bits of all code bits of the FEC codeword into the second frame portion of the frame.

6. A receiving apparatus for a low throughput network, the receiving apparatus comprising:

a frame extraction section configured to extract one or more frames from a received transport stream, a frame comprising payload data encoded as FEC codewords having respective predetermined codeword lengths and having a predetermined frame length, wherein a frame comprises a first frame portion having a first predetermined length being an integer multiple of the predetermined codeword length and a second frame portion having a second predetermined length being shorter than the predetermined codeword length, wherein the frame extraction section is configured to extract FEC codewords and a predetermined number of repetitions of the FEC codewords from the first frame portion of a frame and to extract a selected number of bits of the FEC codewords from the second frame portion of the frame, and

an FEC decoder configured to decode payload data from the FEC codeword extracted from the frame, the repetitions of the FEC codeword, and a selected number of bits of the FEC codeword;

wherein evenly distributed parity bits of all parity bits of the FEC codeword or evenly distributed code bits of all code bits of the FEC codeword are included into the second frame portion of the frame.

7. A receiving method for a low throughput network, the receiving method comprising:

extracting one or more frames from the received transport stream, a frame comprising payload data encoded as FEC codewords having respectively a predetermined codeword length and a frame having a predetermined frame length, wherein a frame comprises a first frame portion having a first predetermined length being an integer multiple of the predetermined codeword length and a second frame portion having a second predetermined length being shorter than the predetermined codeword length by extracting FEC codewords and a predetermined number of repetitions of the FEC codewords from the first frame portion of the frame and by extracting a selected number of bits of the FEC codewords from the second frame portion of the frame, and

decoding payload data from the FEC codeword extracted from the frame, the repetitions of the FEC codeword, and a selected number of bits of the FEC codeword;

wherein uniformly distributed parity bits of all parity bits of the FEC codeword or uniformly distributed code bits of all code bits of the FEC codeword are included into the second frame portion of the frame.

8. A non-transitory computer-readable recording medium having stored therein a computer program product, which when executed by a processor, causes the method according to claim 5 or 7 to be performed.